[tex-live] mf segfault

Olaf Weber olaf at infovore.xs4all.nl
Tue Dec 28 19:26:57 CET 2004

Thorsten Dahlheimer writes:
> Nelson H. F. Beebe wrote:

>>>> The example Metafont code uses so many independent variables
>>>> (at least 2^25) that the serial number counter (the serial_no
>>>> variable) overflows and becomes negative. But Metafont's internal
>>>> routines assume that serial numbers are positive.

>> Congratulations!  You've just uncovered a bug in Metafont that Don
>> will very likely fix (but not soon).  You should propose a patch
>> that we can incorporate in TeXlive Metafont releases until Don
>> makes an official change.  If he accepts your bug report (send it
>> to Barbara Beeton, who privately coordinates such things with Don),
>> you'll get a nice check to cash (or frame).

> Ok, I've attached a change file that adds an overflow check
> for serial_no. It will trigger a fatal error if the largest
> possible value has been reached.

FWIW, I've added the proposed code to the metafont and metapost change
files for web2c.

Lots of thanks for tracking this one down.

Olaf Weber

               (This space left blank for technical reasons.)

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